In six Centers belonging to the Italian Movement Disorder Study Group, the efficacy of botulinum toxin treatment was evaluated in an open collaborative study in 251 patients with focal dystonia and hemifacial spasm. The percentage of functional improvement ranged from 66% to 81% in patients with blepharospasm, from 40% to 51% in patients with spasmodic torticollis and from 73% to 81% in those with hemifacial spasm. Good results were also obtained in patients with oromandibular dystonia, laryngeal dystonia and writer's cramp. Side effects were mild and transient. Local botulinum toxin injection is the first choice symptomatic treatment in focal dystonia and hemifacial spasm.